Man, this has been a week for Valve news. Time for some bad. It looks like Valve has been hit by some sort of intrusion that has resulted in the entire Source codebase from 2007 being leaked.
This leak, though years out of date at this point, contains all sorts of code relating to the Steam API and other tools, including code that was unused or used strictly internally by Valve. Depending on how much the Source codebase has changed in the five years of iterations since this leaked version, it could potentially give hackers ammunition for future attacks.
The attack appears to have been carried out by a group of Russian hackers. The popular theory seems to be that they managed to IP spoof servers typically used by Valve licensees to download Source, posing as a legitimate licensee to download the code base from Valve servers. Of course it’s also completely possible that this code was stolen back in 2007-2008 and only recently released by whoever had it.
The code is currently going around various hacker forums, where the general opinion seems to be that this leak was genuine. The code references various Valve games that were in development at the time, and contains “Last Modified Date”s from January 2008. Before you ask, no, there doesn’t seem to be anything significant relating to Half-Life 3 or Episode 3, though apparently plenty of stuff relating to Beta versions of TF2 are being dug up.
This isn’t the first time Valve’s fallen victim to hackers. Back in 2003 Valve’s internal network was cracked, resulting in a massive leak that included early playable versions of Half-Life 2, Half-Life Source and Counter-Strike Source. The leak was such a big deal that Half-Life 2 ended up getting pushed back to 2004.